Confused about stress

We have 6 Blue Dream clones and are kinda having some problems. Noticed that the leaves were different shades of green and are showing classic signs of nutrient overdose however, after sampling the soil this afternoon we discovered that the soil did not have all that many nutrients in it after all. Now the confusion is did the plants eat all the nutes or is there an excess salt build up. Also if not nutrient problems, then what else could cause the leaf color varying so much and the drooping of the leaf tips. We are currently using Foxfarm Ocean Forest. We tried adding 3 tablespoons of Foxfarm BigBloom and 3-4 drops of super-thrive into a 4.5 gal. rez. through our drippers about a week ago. The plants live in a 6.4' Cubed tent in 3 gallon pots, under a 600w HPS in a Sun system air cooled reflector, environmental controls, A/C, and co2 are in the package. We appreciate any input!

P.S. The results of the samples:
Plant 1 substrate sample taken results: PH 7.1, 250 (TDS P.P.M.)
Plant 2 substrate sample taken results: PH 7.3, 250 (TDS P.P.M.)
Plant 3 substrate sample taken results: PH 7.0, 350 (TDS P.P.M.)
Plant 4 substrate sample taken results: PH 7.4, 250 (TDS P.P.M.)
Plant 5 substrate sample taken results: PH 7.2, 320 (TDS P.P.M.)
Plant 6 substrate sample taken results: PH 7.0, 340 (TDS P.P.M.)

YEah man your PH is a little high for your stage of growth. IMO It should be 6.3-6.5 at this stage and 6.5-6.8 the last 3 weeks or so.
Thats why you are seeing the leaf discoloration.
remedy,
Flush 3 times the amount of the container. let dry, then start nutes back up with a PH of 6.3-6.5. If it was me I would raise the light till I got them back on track
setup looks good man.

any recommendations on methods for flushing? additives? plain ph'd R/O?

john doper said:

any recommendations on methods for flushing? additives? plain ph'd R/O?

Click to expand...

Just plain ph'd R/O

hey thanks man, got the light raised, getting to work on making some R/O. Any other tips from what you can see?

Nah man your Set up is really nice.!!!! I can't see but you might wanna put a fan up that rakes across the canopy. Just watch the basics and they will grow and you will have a heavy harvest. This site has lots of great info and you can really learn a lot..I always tell folks about a guy called Uncle Ben. Hes known for uncle Ben topping technique, but he has lots of great info about growing.
Good luck and Heavy harvest.